Relative water content, membrane stability index and DAB assay in relation to reduction in yield components and resource remobilisation under water stress in common bean (Phaseolus vulgaris L.)

The present study reports use of relative water content (RWC), membrane stability index (MSI), DAB (Diaminobenzidine) assay and yield parameters for screening drought tolerance in common bean. Highest reduction in RWC was recorded for SR-1 (26.11%) while as lowest decrease was observed in case of WB-451 (2.97%). Membrane stability index values under water stress were lowest in case of SR-1 (0.113) followed by WB-257 (0.189) and WB-185 (0.220), where as it was highest in case WB-83 (0.814) followed by WB-401 (0.751) and WB-341 (0.735). Invariably, genotypes with better yield performance and better resource remobilisation had better values of membrane stability index (MSI) under stress. Largest reduction in pod length was observed in case of SR-1 (44.52) followed by WB-1587 (26.34) and WB-83 (22.58) while as smallest reduction was recorded for WB-341 (8.96%). WB-6 and Arka Anoop suffered largest reductions in seed weight (18.93 and 17.45% respectively) while as lowest reduction was recorded in case of WB-1634 (5.74%). Largest reduction in seed yield under drought was observed in case of WB-6 (55.09%) followed by WB-1492 ((51.86%), whereas lowest reduction was recorded for WB-1634 (11.33%). Largest decrease under drought was recorded for seed yield per plant followed by pods per plant, whereas lower decrease was recorded for 100-seed weight. DAB (3, 3-Diaminobenzidene) assay clearly differentiates the lines on the basis of darker staining of leaves under water stress. The lines showing greater per cent reductions in yield parameters show greater staining in DAB assay underlining the reliability of using this assay as a reliable supplement to phenotyping protocols for characterising large germplasm sets.